#La Soufriere - Monday's update

Following is the Monday 19 April update from the UWI Seismic Research Centre (SRC) which is monitoring La Soufriere volcano in St. Vincent and the Grenadines.

Today's update follows the latest explosive eruption which took place on Sunday at 4:49 pm. That eruption came 52 hours after the previous explosive event. There have now been at least 30 explosive events since the start of this explosive phase on Friday 9 April.

UWI Seismic Research Centre (SRC) La Soufriere, St. Vincent SCIENTIFIC UPDATE 19.04.21 6:00AM

1. The episode of continuous seismic tremor generated by explosive activity at La Soufrière, lasted until about 9 pm on 18 April.

• Following this, small long-period and hybrid earthquakes started to be recorded again, at a rate similar to before the explosive activity. This rate dropped significantly at about 1 am on 19 April.

• No volcano-tectonic earthquakes were recorded in the last 12 hours.

• One rockfall was recorded, at 1:39 am. Rockfalls can be generated by a growing lava dome, but this cannot be confirmed without visual observations.

• The continuous GPS network has shown a change in horizontal and vertical movement since the initial depressurization noted immediately following the April 9 explosive phase.

• The continuous GPS (Global Positioning System) network is used to track changes in ground shape on and around the volcano. As magma moves beneath the volcano, changes in pressure cause the volcano to change shape (inflate/deflate).

• These changes may suggest magma influx from deep within the sub-volcanic system, however more investigation is needed to confirm this interpretation.

• The volcano continues to erupt. Its pattern of seismic activity over the last few days is typical of the growth and destruction of lava domes.

• Explosions with accompanying ashfall, of similar or larger magnitude, can occur with little or no warning impacting St. Vincent and neighbouring islands.

1. The volcano is at alert level Red

1. Visit thttps://volcanoes.usgs.gov/volcanic_ash/resources.html for Global Ash Impact posters. These are the latest research-informed material for concise best practice information for critical infrastructure managers to effectively manage ash-producing volcanic eruptions.

12. Visit the International Volcanic Hazard Health Network for volcanic ash information and resources: www.ivhhn.org/information

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